* Newton's First Law of Motion (Law of Inertia): An object at rest will stay at rest, and an object in motion will stay in motion at a constant velocity, unless acted upon by an unbalanced force.

* Balanced Forces: When forces are balanced, they cancel each other out. This means that even though forces are acting on the object, they don't cause it to accelerate.

Examples:

* A book on a table: Gravity pulls the book down, but the table pushes back with an equal and opposite force, keeping the book stationary.

* A car parked on a hill: Gravity pulls the car downhill, but friction from the brakes and tires holds it in place.

* A person standing still: Gravity pulls the person down, but the ground pushes back with an equal and opposite force.

Important Note: Just because an object is at rest doesn't mean there are *no* forces acting on it. It means that the forces are balanced, resulting in no net force and no acceleration.